In U.S. Pat. No. 2,852,554, D. C. England discloses the reaction of hexafluoropropene with freshly distilled, liquid, anhydrous sulfur trioxide to obtain 2-hydroxy-1-trifluoromethyl-1,2,2-trifluoroethanesulfonic acid sultone (hexafluoropropene sultone) of the formula ##STR1## D. C. England, M. A. Dietrich and R. V. Lindsey in "Reaction of Fluoroolefins with SO.sub.3 ", J. Amer. Chem. Soc., 82, 6181 (1960) also report the reaction of hexafluoropropene (HFP) with freshly distilled sulfur trioxide (SO.sub.3) at 100.degree. C. to give the sultone of HFP ##STR2## This reference (p. 6184) also reports the reaction of hexafluoropropene with inhibited SO.sub.3 at 60.degree. C. to give an unidentified mixture, b.p. 50.degree.-65.degree. C., and a high-boiling product which presumably is a cyclic sulfonate-sulfate anhydride of the formula ##STR3##
M. A. Belaventsev, L. L. Mikheev, V. M. Pavlov, G. A. Sokol'skii and I. L. Knunyants, Izv. Akad, Nauk SSSR, Ser. Khim. 1972 (11), 2510-16 (Russ), Eng. Trans. 2441-2445, disclose the reaction of (CF.sub.3).sub.2 C=CF.sub.2 with SO.sub.3 at 150.degree.-180.degree. C. to give ##STR4##